Chapter

ClimateClimate

21.1 Factors That Affect Climate

Latitude

• As latitude increases, the intensityof solar energy decreases.

• The tropical zone is between 23.5o

north (the tropic of Cancer) and23.5o south (the tropic of Capricorn)of the equator. The sun’s rays aremost intense and the temperaturesare always warm.

21.1 Factors That Affect Climate

Latitude

• The temperate zones are between• The temperate zones are between23.5o and 66.5o north and between23.5o and 66.5o south of theequator. The sun’s rays strike Earthat a smaller angle than near theequator.

Earth’s Major Climate Zones

21.1 Factors That Affect Climate

Latitude

• Polar zones are between 66.5o

north and south latitudes and thepoles. The sun’s rays strike Earthpoles. The sun’s rays strike Earthat a very small angle in the polarzones.

Elevation• The higher the elevation is, the

colder the climate.

21.1 Factors That Affect Climate

Topography

• Topographic features such as• Topographic features such asmountains play an important role inthe amount of precipitation thatfalls over an area.

The Rain Shadow Effect

21.1 Factors That Affect Climate

Water Bodies

• Large bodies of water such as• Large bodies of water such aslakes and oceans have animportant effect on the temperatureof an area because the temperatureof the water body influences thetemperature of the air above it.

21.1 Factors That Affect Climate

Atmospheric Circulation

• Global winds are another factorthat influences climate becausethat influences climate becausethey distribute heat and moisturearound Earth.

21.1 Factors That Affect Climate

Vegetation

• Vegetation can affect both• Vegetation can affect bothtemperature and the precipitationpatterns in an area.

The Köppen Climate Classification System

21.2 World Climates

The Köppen climate classificationsystem uses mean monthly andsystem uses mean monthly andannual values of temperature andprecipitation to classify climates.

21.2 World Climates

Humid tropical climates arewithout winters. Every month insuch a climate has a meantemperature above 18oC. Theamount of precipitation can exceed

Humid Tropical Climates

temperature above 18 C. Theamount of precipitation can exceed200 cm per year.

Wet Tropical• Wet tropical climates have high

temperatures and much annualprecipitation.

Rain Forest in Malaysia

Rain Forest in Malaysia

Humid Tropical Climates

21.2 World Climates

Tropical Wet and Dry• Tropical wet and dry climates are

climates that transition between theclimates that transition between thewet tropics and the subtropicalsteppes.

African Savanna

African Savanna

Humid Mid-Latitude Climates

21.2 World Climates

Climates with mild winters havean average temperature in thecoldest month that is below 18oCcoldest month that is below 18oCbut above -3oC.

Climates with severe winters havean average temperature in thecoldest month that is below -3oC.

21.2 World Climates

Humid Mid-Latitude with MildWinters

• A humid subtropical climate isgenerally located on the eastern side

• A humid subtropical climate isgenerally located on the eastern sideof a continent and is characterizedby hot, sultry summers and coolwinters.

21.2 World Climates

Humid Mid-Latitude with Mild Winters

• A marine west coast climate isfound on windward coasts fromlatitudes 40o to 65o and islatitudes 40o to 65o and isdominated by maritime air masses.Winters are mild, and summers arecool.

East

West

Humid Mid-Latitude Climates

21.2 World Climates

Humid Mid-Latitude With MildWinters

• A dry-summer subtropical climate• A dry-summer subtropical climateis a climate located on the westsides of continents between 30o

and 45o latitude. It is the onlyhumid climate with a strong winterprecipitation maximum.

21.2 World Climates

Humid Mid-Latitude With Severe Winters

• A subarctic climate is found northof the humid continental climateand south of the polar climate; it isand south of the polar climate; it ischaracterized by bitterly coldwinters and short, cool summers.Places within this climate realmexperience the highest annualtemperature ranges on Earth.

Dry Climates

21.2 World Climates

A dry climate is one in whichthe yearly precipitation is notthe yearly precipitation is notas great as the potential loss ofwater by evaporation.

Polar Climates

21.2 World Climates

Polar climates are those inwhich the mean temperature ofthe warmest month is below10oC.

An Ice Cap Climate Is a Polar Climate

Highland Climates

21.2 World Climates

In general, highland climates In general, highland climatesare cooler and wetter thannearby areas at lowerelevations.

Natural Processes That Change Climates

21.3 Climate Changes

Volcanic Eruptions

• The presence of volcanic aerosols(ash, dust, and sulfur-based

• The presence of volcanic aerosols(ash, dust, and sulfur-basedaerosols) in the air increases theamount of solar radiation that isreflected back into space. Thiscauses Earth’s lower atmosphereto cool.

Natural Processes That Change Climates

21.3 Climate Changes

Ocean Circulation

• Changes in ocean circulation alsocan result in short-term climatefluctuations.

Eruption of Mount Pinatubo

Effect of El Niño

Natural Processes That Change Climates

21.3 Climate Changes

Solar Activity• When the sun is most active, it

contains dark blemishes calledcontains dark blemishes calledsunspots. The formation ofsunspots appears to correspondwith warm periods in Europe andNorth America.

Natural Processes That Change Climates

21.3 Climate Changes

Earth Motions

• Geographic changes in Earth’s• Geographic changes in Earth’sland and water bodies causechanges in climate.

• Changes in the shape of Earth’sorbit and the tilt of Earth on its axisare other Earth motions that affectglobal climates.

Human Impact on Climate Changes

21.3 Climate Changes

The Greenhouse Effect

• The greenhouse effect is a natural• The greenhouse effect is a naturalwarming of both Earth’s loweratmosphere and Earth’s surfacefrom solar radiation beingabsorbed and emitted by theatmosphere.

GlobalWarming

• As a result of increased levels ofcarbon dioxide and othergreenhouse gases, globaltemperatures have increased. Thisincrease is called global warming.

Carbon Dioxide Concentrationsand Emissions

Increases in Greenhouse Gasesand Changes in Temperature